A water-soluble, cell-permeable Mn(ii) sensor enables visualization of manganese dynamics in live mammalian cells

Kahali, S and Das, SK and Kumar, R and Gupta, K and Kundu, R and Bhattacharya, B and Nath, A and Venkatramani, R and Datta, A (2024) A water-soluble, cell-permeable Mn(ii) sensor enables visualization of manganese dynamics in live mammalian cells. In: Chemical Science .

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Abstract

Central roles of Mn2+ ions in immunity, brain function, and photosynthesis necessitate probes for tracking this essential metal ion in living systems. However, developing a cell-permeable, fluorescent sensor for selective imaging of Mn2+ ions in the aqueous cellular milieu has remained a challenge. This is because Mn2+ is a weak binder to ligand-scaffolds and Mn2+ ions quench fluorescent dyes leading to turn-off sensors that are not applicable for in vivo imaging. Sensors with a unique combination of Mn2+ selectivity, μM sensitivity, and response in aqueous media are necessary for not only visualizing labile cellular Mn2+ ions live, but also for measuring Mn2+ concentrations in living cells. No sensor has achieved this combination thus far. Here we report a novel, completely water-soluble, reversible, fluorescent turn-on, Mn2+ selective sensor, M4, with a Kd of 1.4 μM for Mn2+ ions. M4 entered cells within 15 min of direct incubation and was applied to image Mn2+ ions in living mammalian cells in both confocal fluorescence intensity and lifetime-based set-ups. The probe was able to visualize Mn2+ dynamics in live cells revealing differential Mn2+ localization and uptake dynamics under pathophysiological versus physiological conditions. In a key experiment, we generated an in-cell Mn2+ response curve for the sensor which allowed the measurement of the endogenous labile Mn2+ concentration in HeLa cells as 1.14 ± 0.15 μM. Thus, our computationally designed, selective, sensitive, and cell-permeable sensor with a 620 nM limit of detection for Mn2+ in water provides the first estimate of endogenous labile Mn2+ levels in mammalian cells. © 2024 The Royal Society of Chemistry.

Item Type:	Journal Article
Publication:	Chemical Science
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to authors.
Keywords:	Cytology; Dynamics; Fluorescence imaging; Lanthanum compounds; Mammals; Metal ions; Probes, Brain functions; Cell-permeable; Cellular milieus; Essential metals; Fluorescent sensors; Living systems; Mammalian cells; Metals ions; Selective imaging; Watersoluble, Manganese compounds
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	21 Dec 2024 05:45
Last Modified:	21 Dec 2024 05:45
URI:	http://eprints.iisc.ac.in/id/eprint/85919

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